Actin Structure-Dependent Stepping of Myosin 5a and 10 during Processive Movement
Myosin stepping model on F-actin rafts. Two heads of myosin (light brown color) bind on an actin monomer (green) in actin filaments. The center of the mass of the myosin is depicted by a red circle. When myosin steps forward (black arrow), the detached head binds a new actin monomer (green). (A) The model for stepping on fascin-F-actin rafts. Left-hand side shows the myosin molecule stepping forward along an actin filament in the rafts. The length of the red arrow represents the magnitude of the step-size. Black arrows represent the direction of the stepping. Right-hand side model shows a myosin molecule taking a side step to an adjacent actin filament in the rafts. Note that when a myosin takes a side step onto an adjacent actin filament the center of mass movement takes two short steps. Yellow arrow represents the direction of actin filament in the rafts. (B) The model of stepping on α-actinin-F-actin rafts. A myosin molecule cannot reach an adjacent actin filament and thus cannot have a side step.